drm: BIT(DRM_ROTATE_?) -> DRM_ROTATE_?

Only property creation uses the rotation as an index, so convert the
to figure the index when needed.

v2: Use the new defines to build the _MASK defines (Sean)

Cc: intel-gfx@lists.freedesktop.org
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: malidp@foss.arm.com
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: Sean Paul <seanpaul@chromium.org>
Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1469771405-17653-1-git-send-email-joonas.lahtinen@linux.intel.com